drop table machine_c;

create table machine_c(
	machince_no number primary key,
 	component_id number,
 	working_start varchar2(30),
 	working_end varchar2(30),
 	is_fault varchar(1),
 	constraint c_component_code_fk foreign key(component_id) REFERENCES component(component_id)
);

select machineC.nextval from dual

drop sequence machinceC

DROP SEQUENCE machinceC;

create sequence machineC